Debt and Commitments (Details Narrative) (USD $)	12 Months Ended				0 Months Ended	12 Months Ended					12 Months Ended				12 Months Ended								12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 Line of Credit [Member]	Apr. 05, 2011 Convertible Debt [Member] 3.75% Convertible Notes [Member]	Dec. 31, 2009 Convertible Debt [Member] 3.75% Convertible Notes [Member]	Dec. 31, 2011 Convertible Debt [Member] 3.75% Convertible Notes [Member]	Dec. 31, 2010 Convertible Debt [Member] 3.75% Convertible Notes [Member]	Apr. 05, 2011 Convertible Debt [Member] 3.75% Convertible Notes [Member] Redeemed With Accrued Interest [Member]	Apr. 05, 2011 Convertible Debt [Member] 3.75% Convertible Notes [Member] Surrendered For Conversion [Member]	Dec. 31, 2011 Convertible Debt [Member] 3.375% Convertible Notes [Member] D	Dec. 31, 2009 Convertible Debt [Member] 3.375% Convertible Notes [Member]	Dec. 31, 2010 Convertible Debt [Member] 3.375% Convertible Notes [Member]	Dec. 31, 2007 Convertible Debt [Member] 3.375% Convertible Notes [Member]	Dec. 31, 2009 Convertible Debt [Member] 3.75% and 3.375% Convertible Notes [Member]	Dec. 31, 2011 Revolving Credit Agreement [Member]	Sep. 26, 2011 Revolving Credit Agreement [Member]	Dec. 31, 2010 Revolving Credit Agreement [Member]	Dec. 31, 2011 Line of Credit [Member]	Dec. 31, 2010 Line of Credit [Member]	Dec. 31, 2011 Minimum [Member] Revolving Credit Agreement [Member]	Dec. 31, 2011 Maximum [Member] Revolving Credit Agreement [Member]	Dec. 31, 2011 On Or Before September 30 2013 [Member] Minimum [Member] Revolving Credit Agreement [Member]	Dec. 31, 2011 On Or Before September 30 2013 [Member] Maximum [Member] Revolving Credit Agreement [Member]	Dec. 31, 2011 After September 30 2013 [Member] Minimum [Member] Revolving Credit Agreement [Member]	Dec. 31, 2011 After September 30 2013 [Member] Maximum [Member] Revolving Credit Agreement [Member]	Dec. 31, 2009 Treasury Stock [Member]
Debt Instrument [Line Items]
Convertible notes stated interest rate							3.75%				3.375%
Convertible notes							$ 0	$ 92,500,000	$ 11,865,000	$ 80,635,000	$ 55,636,000		$ 55,636,000			$ 281,900,000		$ 207,900,000	$ 12,000,000	$ 0
Repayments of convertible debt, including premium on conversion					90,438,000
Premium paid on convertible debt redemption	9,803,000	0	0		9,803,000
Adjustments to additional paid in capital, premium paid on convertible debt redemption					6,085,000
Adjustments to additional paid in capital, income tax benefit from premium paid on convertible debt redemption, tax					3,718,000
Adjustments to additional paid in capital, income tax benefit on convertible debt redemption, tax															2,585,000
Contingent convertible debt interest, amount recaptured for income tax purpose					40,217,000
Reduction in short-term deferred tax liabilities					15,252,000
Deferred tax assets, noncurrent, operating loss carryforwards, reduction for convertible notes redemption					15,252,000
Debt instrument, face amount														100,000,000
Debt instrument, convertible, conversion ratio											35.3235
Debt instrument, convertible, conversion price											$ 28.31
Number of days used to calculate highest average stock price											20
Total pool of days used to calculate the highest average stock price											30
Minimum ratio of stock price to conversion price for conversion											130.00%
Guaranteed cash payment upon conversion per note											1
Debt instrument, convertible, eligible for conversion	0	0
Convertible note repurchases, par value						7,500,000						44,364,000
Convertible note repurchases, cash consideration															28,651,000
Convertible note repurchases, shares	0	0													1,154,265												1,154,265
Convertible note repurchases, value			17,019,000												17,019,000
Convertible note repurchases, total consideration															45,669,000
Convertible note repurchases, portion of toal consideration attributed to debt component															38,852,000
Convertible note repurchases, portion of toal consideration attributed to equity component															6,817,000
Long-term debt, gross, net of unamortized discounts	346,052,000	357,718,000					0	92,386,000			50,303,000		48,259,000		43,560,000
Convertible note repurchases, unamortized debt discount							0	114,000			5,333,000		7,377,000		8,304,000
Adjustments to additional paid in capital, equity component of convertible debt, subsequent adjustments	5,238,000														4,232,000
Write off of deferred debt issuance cost															934,000
Gains (losses) on extinguishment of debt	0	0	3,773,000												3,773,000
Extinguishment of debt, gain (loss), net of tax															2,342,000
Line of credit facility previous maximum borrowing capacity				15,000,000												500,000,000	400,000,000
Line of credit expiration date extension																4 years
Line of credit facility, amount outstanding				12,000,000												281,900,000
Line of credit facility remaining borrowing capacity																218,100,000
Debt instrument basis spread on LIBOR																					1.10%	1.70%
Line of credit facility, interest rate at period end				2.17%												1.49%		1.01%
Debt covenant ratio of senior debt to EBITDA																								3.25		3.00
Debt covenant ratio of total debt to EBITDA																								4.00		3.75
Debt covenant ratio of EBITDA to cash interest expense																							4.25		4.50
Payments of debt issue costs																2,012,000
Foreign bank borrowings and overdrafts	1,849,000	6,955,000
Letters of credit outstanding, amount	$ 7,146,000